Integrally gated carbon nanotube field ionizer device and method of manufacture therefor

Abstract

A field ionization device can include a first insulator layer on a first side of a substrate, a conductive gate layer on the first insulator layer, a cavity in the substrate, a portion of first insulator over the cavity, an aperture in the portion of the first insulator layer and the conductive gate layer thereby forming an aperture and aperture sidewall. The device can include a second insulator layer on the aperture sidewall and surface of the cavity, a metallization layer over the second insulator layer, a catalyst layer on the metallization layer, and a carbon nanotube. The cavity can be made by etching a second side of the substrate to near the insulator layer, wherein the second side is opposite the first side. The carbon nanotube can be grown from the catalyst layer. The device can further include a collector located near the carbon nanotube. The conductive gate layer can be biased negative with respect to the carbon nanotube. An electric field can exist between the carbon nanotube and the conductive gate layer. Another embodiment can include an array of multiple devices as described herein wherein the multiple devices are in close proximity to each other. Also provided is a method of making the device.

1. An integrally gated carbon nanotube field ionizer device comprising:
 a substrate containing a cavity and a gate; 
 a first insulator layer positioned between said substrate and said gate; 
 an aperture in said gate and said first insulator layer forming an interior wall; 
 a second insulator layer on said interior wall; 
 a metallization layer on said second insulator layer; 
 a catalyst layer on said metallization layer; 
 a carbon nanotube on said catalyst layer and in electrical contact with the substrate and electrically insulated from the gate; 
 a collector; 
 wherein the gate is biased negative with respect to the carbon nanotube and substrate; 
 wherein the collector is biased more negative than the gate; 
 wherein an analyte is channeled and field ionized via the cavity from the backside and through to contact the carbon nanotube; and 
 wherein the resulting positive ion is then accelerated toward the collector. 
 
     
     
       2. The device of  claim 1  wherein a gas has access to said carbon nanotube via channeling through the cavity from the backside and field ionized. 
     
     
       3. The device of  claim 1  wherein a liquid containing analytes has access to said carbon nanotube via channeling through the cavity from the backside and field ionized. 
     
     
       4. The device of  claim 1  wherein said substrate is a semiconductor or a conductor. 
     
     
       5. The device of  claim 1  wherein said insulator is a high resistivity material such as silicon dioxide or silicon nitride. 
     
     
       6. The device of  claim 1  wherein said metallization layer is a conductor with strong adhesion to said second insulator and is selected from the group consisting of Cr, Ti, W, Ta, and TiN. 
     
     
       7. The device of  claim 1  wherein said catalyst layer is selected from the group consisting of Ni, Co. Fe, Pd, alloys thereof, and combinations thereof. 
     
     
       8. The device of  claim 1  further comprising multiple carbon nanotubes. 
     
     
       9. The device of  claim 1  wherein said carbon nanotube is located near the top of said metallization layer. 
     
     
       10. The device of  claim 1  wherein said carbon nanotube is located on said interior wall. 
     
     
       11. The device of  claim 1  wherein said catalyst layer resides on said metallization layer only in said aperture. 
     
     
       12. The device of  claim 1  wherein said metallization layer in said aperture is the catalyst layer. 
     
     
       13. A field ionization device comprising an array of multiple devices as in  claim 1 . 
     
     
       14. An integrally gated carbon nanotube field ionizer device comprising:
 a first insulator layer on a first side of a substrate: 
 a conductive gate layer on said first insulator layer; 
 a cavity in said substrate; 
 a portion of said first insulator layer over said cavity; 
 an aperture in said portion of said first insulator layer and said conductive gate layer thereby forming an aperture sidewall; 
 second insulator layer on said aperture sidewall on said first insulator layer and optionally surface of said cavity; 
 a metallization layer over said second insulator layer; 
 catalyst layer on said metallization layer on sidewall of said second insulator on said aperture sidewall; 
 a carbon nanotube on said catalyst layer and in electrical contact with the substrate and electrically insulated from the gate; 
 a collector; 
 wherein the gate is biased negative with respect to the carbon nanotube and substrate; 
 wherein the collector is biased more negative than the gate; 
 wherein an analyte can be channeled and field ionized via the cavity from the backside and through to contact the carbon nanotube; and 
 wherein the resulting positive ion is then accelerated toward the collector. 
 
     
     
       15. The device of  claim 14  wherein said cavity is made by etching a second side of said substrate to near said first insulator layer, wherein said second side is opposite said first side. 
     
     
       16. The device of  claim 14  wherein said carbon nanotube is grown from said catalyst layer on said metallization layer on said second insulator layer on said aperture sidewall. 
     
     
       17. The device of  claim 14  in said metallization layer on said sidewall of said second insulator on said aperture sidewall is the catalyst layer. 
     
     
       18. The device of  claim 14  further including a collector located
 near said carbon nanotube and wherein said collector is biased more negative than said conductive gate layer. 
 
     
     
       19. The device of  claim 14  further including an electric field
 between said carbon nanotube and said conductive gate layer. 
 
     
     
       20. The device of  claim 14  wherein a gas flows through said aperture in said substrate and in said first insulator layer, said second insulator layer, said metallization layer and said conductive gate layer. 
     
     
       21. The device of  claim 14  wherein a liquid containing analytes flows through said aperture in said substrate and said first insulator layer, second insulator layer, said metallization layer, and said conductive gate layer.